Catalytic oxidation of ortho-cresol



'catalyzers.

UNITED STATES PATENT OFFICE.

JOHN M. WEISS,

JERSEY, ASSIGNORS TO THE BARRETT 00 OF NEW YORK, N. Y., AND CHARLES R.DOWNS, OF OLIFFSIDE, NEW

MPANY, A CORPORATION OF NEW JERSEY.

CATALYTIC OXIDATION OF OBTHO-GRESOL.

No Drawing.

To all whom it may concern:

Be it known that we, JOHN M. Wnrss and CHARLES R. Downs, citizens of theUnited States, residing at (1) 210 West 110th street, New York city, and3g2) Cliffside, in the counties of (1) New ork and 2) Bergen and States(1 New York, (2) ew Jersey, have invente certain ,new and usefulImprovements in Catalytic Oxidation of Ortho Cresol, of which thefollowing is a specification.

This invention relates to the catalytic oxidation of ortho-cresol and tothe production of products of partial oxidation therefrom. It comprisesthe partial or selective oxidation of ortho-cresol by oxidation, eitheralone or mixed with diluents or by means of the oxygen containing gas inthe presence of a catalyzer to form salicylaldehyde, salicylic acid, orboth. The invention is based upon the discovery that by subjectingortho-cresol, 0 1-1 0, to oxidation in the presence of an appropriatecatalyzer, and at an appropriate temperature a selective or partialoxidation thereof takes place with the formation of an oxidation productor products such as salicylaldehyde or salicylic acid. We haveconditions, the ortho-cresol may be changed to salicylaldehyde orsalicylic acid without effecting the complete combustion of a very largeproportion of the material treated. The invention may be practised bysubjecting the ortho-cresol in the vapor phase mixed with air or withoxygen either alone or admixed with other diluent gases or with certainoxygen containing gases, to a suitable temperature in the resence ofcertain I The use of 0 has been found to be especially useful in thisconnection as a diluent gas. It has been found that many oxids of metalsare suitable as catalyzers. More especially iron oxids, alminiumoxid andoxids of the fifth and sixth groups of elements in the periodic system,and more I particularly molybdenum oxid, have been found to beespecially useful as catalyzers in this process.

By suitably regulating the conditions such as temperature, pressure andpresence of diluents and operating with proper 'c'atalysts, the degreeof oxidation can be controlled whereby the ortho-cresol is oxidizedSpecification of Letters Patent.

found that under proper Patented May 31, 1921.

Application fiIed December 12, 1919. Serial No. 344,370.

in a particular manner to an oxidation short of what is commonly knownas complete combustion to produce salicylaldehyde or salicylic acid.

, The invention will be explained in connection with the followingexample, which is given for illustrative purposes. It is not intended tolimit the procedure to the exact details given as the process can bevaried throughout wide limits without departing from the spirit andscope of the invention.

A mixture of ortho-cresol and air in the vapor phase is passed throughtubes at, a temperature of about 250 C. to 500? C., the tubes containingmolybdenum oxid deposited on crushed pumice with the result thatsalicylaldehyde and salicylic acid are produced. Instead of introducingoxygen as oxygen of the air, oxygen gas may be used either alone ordiluted with nitrogen or other inert gas; the proportion of oxygen toorthocresol may be varied; the catalyzer may be deposited on crushedpumice or other suitable powdered, granulated or fibrous material whichis chemically inactive and acts merely as a mechanical distributer; therate at which, the mixture is passed through the tubes may be regulatedto suit the needs;

the tubes may be varied in length or diameter or confined spaces otherthan tubes may be used in which to place the catalyzer; instead ofmolybdenum oxid, other compounds may be used as a catalyzer. It isessential that hot ortho-cresol in the vapor .phase shall come incontact with the catalyzer in the presence of ox gen for the properreaction to take place. he introduction of a diluent gas is a convenientway to assist in regulation of the reaction. It has molecule ofortho-cresol to three atoms of oxygen to produce salicylic acidfromjorthocresol. The following equations are suggested as representingthe reactions which take place, although it is not desired to limit thereactions to any particular theory. The

moist air, instead of dry air,

equations are given to explain the reactions as indicated by the resultsobtained.

+H0 CHO Where considerable excess of ortho-cresol is used over and abovethat which is oxidized, the remaining ortho-cresol will 1n Water ispractically always formed as 'a sures The oxidizing efiect can bedation.

product some steam is present as a consequence.

The ortho-cresol used should preferably be of high purity or if admixedwith impurities, it should be substantially free from impurities of acharacter as would prejudice the desireselectiv and partial catalyticoxi- It' will be evident that various'types of apparatus may beused forcarrying out the process of the present invention and for bringingreactin gases with the catalyst, and for maintaining the propertemperature for the catalytic reaction. Accordingly, we do not deem itnecessa to describe in further detail such types o i apparatus.

It will'be evident also that the various conditions oi: the reaction arecapable of variation. Among these conditions may be mentioned thetemperature and pressure at which the reaction is carried out, the time0t contact of t e reactive gases with the catalyst, the proportion ofcatalyst to the reacting gases,

gases, such,'as nitrogen or CO The reaction may thus be carried out atatmospheric pressure, or at increased or diminished presmodified byfurther diluting the reacting gases, as by returning the air, thereaction, to dilute the reacting gases in the 'further carrying outofthe process,

orby mixing oxygen w1th the air to lncrease,

the. oxygen content thereof, or by using oxy oxygen in admixture withother gases than those contained in air, etc.

It will evident contact of the reacting gases with the catalyst can .bevaried by increasing the catalytic 1 mass or bydecreasing the speed atwhich the reacting gases am through or in contact with the catalyst.These and like variations about the necessary contact of the and therelative pro-portions of ortho-cresol and oxygen and of diluentimpovished in oxygen by i also that the time of I will correspondinglymodify and aifect the catalytic'oxidation.

Salicylaldehyde and salicylic acid areapparently intermediate productsof the incomplete oxidation of ortho-cresol. In the operation of thisprocess, under proper conditions, there has been found to be very littlecom lete combustion, thus indicating that practically all of theortho-cresol which is oxidized is changed to salicylaldehyde or.salicylic acid. .Any of the ortho-cresol which passes through theprocess unchanged maybe separated from the other productsby sublimation,crystallization, distillation, etc, and may again passed through thereaction zone mixed with oxygen'or mixed with a sufiicient supply ofortho-cresol and'oxygen, if desired, and more temperature from about 250C. to 500 C. with an oxygen containing gas in the presence of a metallicoxid as a catalyst.

4. The method of'producing' salicylaldehyde and salicylic acid whichcomprises oxidizing ortho-cresol in the va or phase at a temperature ofabout 250 to 500 C. with an oxy en containing gas in the presence ofmolyhdenum oxid as a catalyst.

5. The method of producing salieylaldeand salicylic acid which comprisesoxi-.

hyde dizing ortho-cresol in the vapor phase with an. oxygen containinggas inthe presence of a metallic oxid as a catalyst, separating thesalicylaldehyde and salicylic acid from any unchanged ortho-cresolandreturning the ortho-cresol'for a similar oxidizing treatment. I

6. The method ofproducing salicylaldehyde and salicylic acid whichcomprises oxidizing ortho-cresol in the vapor phase with an oxygencontaining gasin the-presence of molybdenum oxid as a-catalyst,separatgen alone wihout other diluent, or by using ing thesalicylaldehyde and salicylic acid from any unchanged ortho-cresol andre- -turning the ortho-cresol for a-similar oxi-- dizin treatment.

- 7. he method of roducing salicylalde hyde and salicylic acid whichcomprises oxidizing ortho-cresol in the vapor phase with an oxygencontaining gas in the presence of a metallic oxid as a catalyst, at atempera tureof from about 250 C. to 500 0., sepatemperature of fromabout 250 0. to 500 rating the salicylaldehyde and salicylic acid 0.,separating the salicylaldehyde and salifrom any unchanged ortho-cresoland recylic acid from any unchanged ortho-cresol turning theortho-cresol for a similar oxiand returning the ortho-cresol for asimilar a dizing treatment. oxidizing treatment. 15 8. he method ofproducing salicylalde- In testimony whereof we afiix our signa-' hydeand salicylic acid which comprises oxit'ures. dizingortho-cresol in thevapor phase with an oxygen containing gas in the presence JOHN M. WEISS.10 of molybdenum oxid as a catalyst, at a CHARLES R. DOWNS.

